A Multispecies Exclusion Process Inspired by Intraflagellar Transport: Effects of Fusion and Fission*

Inspired by the “fusion and fission” of Intraflagellar transport (IFT) trains, we have developed a multispecies exclusion model where length-conserving probabilistic fusion and fission of the hard rods are allowed. A monodisperse population of rods of length L=1 enter the system, but their lengths keep fluctuating because of fusion and fission, as they move in a step-by-step manner towards the distal end obeying mutual exclusion. Fusion of two neighboring hard rods of lengths L1 and L2 results in a single rod of longer length L=L1+L2 provided L is less than, or equal to, N, which is the maximum allowed length for a rod inside the system. Similarly, length-conserving fission of a rod results in two shorter daughter rods. The density- and the flux-profiles of the rods are in excellent agreement with computer simulations and leads to a ‘transition zone’ in the fusion dominated regime. The insights gained from this simple model, emerging from the interplay of fusion and fission, are likely to have important implications for IFT and for other similar transport phenomena in long cell protrusions.